Some of my concerns: - Ever since a few people have made a fortune from the massive spike in prices, it's attracted a lot of traders and day traders. Not a bad thins but it's clear to me that easily 90% of cryptocurrency users are just traders with no intensions of using the currencies. Hence the rise in a lot of exchanges (a lot of which look the same).
- All it takes is 51%. Although for a coin such as BTC would be very expensive to attack the network it's still possible.
Here's my insane scenario:
100 top banks from across the world don't like the threat BTC has on their business so they all join together to buy compute power, take over the network and cause havoc. I estimate it would cost around $2,000,000,000 (2 Billion USD). This is very expensive but what's $20,000,000 (20 million USD) to a top bank? That's an investment to help protect their business. - Speed: BTC is known to be slow to confirm a single transaction (approx 10 mins). ETH is faster (approx 15 seconds). I believe (correct me if i'm wrong) that if you cut down block times it slowly starts to make a decentralised system more centralised.
It's true that trading is the most popular use right now, but it doesn't mean that it will keep being that way forever. It's just an observation, not a prediction.
As for 51% attack - it's not about just amassing hash power, you also need to constantly burn electricity to sustain it, which is why Bitcoin is so resilient. It's really not a big threat to Bitcoin thanks to how it was designed.
Speed - Lightning network takes care of it. And you comparison with ETH or other shitcoins is wrong, because 1 confirmation in Bitcoin has different amount of security than 1 confirmation in ETH.